Leiomyoma uteri is a monoclonal tumour of the uterus muscle layer. It is characterized by excessive, abnormal growth of extracellular matrix. The collagen types I and III are the major components of extracellular matrix. Removal of the C-propeptides in procollagens type I, II, and III by procollagen C-endopeptidase leads to spontaneous self-assembly of collagen fibrils. Thus, the procollagen C-endopeptidase is a key regulator of extracellular matrix production, its quality, and other developmental processes including angiogenesis.
Objective: The objective of this study was to analyze the three alternatively spliced variants of the BMP1 gene product including the procollagen C-endopeptidase, in leiomyoma uteri tumors in comparison to normal myometrium in women being in first or second menstrual phase or in time of climacterium.
Material and methods: In the study we analyzed samples from the control and cancerous tissues from 52 women. Expression of the three alternatively spliced variants of BMP1 gene transcript were assayed by RT-PCR, following densytometric analysis. Statistical significance (p < or = 0,05) of the observed differences was assessed with the use of Anova test, Least Significance Different Test, and Student's T-test.
Results: Analysis of RT-PCR products revealed the presence of all alternatively spliced variants of BMP-1 mRNA and the changes in their alternative splicing intensity, depending on the phase of menstrual cycle or postmenopausal state. In the second phase of the cycle, in control tissue, the expression level of BMP-1 variant decreased when compared to women in I phase of the cycle or postmenopausal women. In the tumour, postmenopausal women showed increased expression of BMP-1at, when compared with women in the second phase of the cycle. The presence of mTLD in the tumour tissue at II phase of the cycle and in postmenopausal state was less strong when compared to women at I phase of the cycle. In control tissue this type of change was not observed. The BMP-1/HIS was present at higher level in control tissue, during II phase of the menstrual cycle and in postmenopausal state, whereas in the tumour tissue its lowest level was at II phase of the cycle.
Conclusions: Regulation of alternative splicing of mRNA for procollagen C-endopeptidase in leiomyomas and myometrium depends mainly on the hormonal status of women.